Up to now, as a photosensitive polyimide system material, there has been proposed a material which employs a polyamic acid (polyimide precursor), such as a material in which a photosensitive group is introduced into carboxyl group of polyamic acid via ester bonding (JP-A-49-115541, JP-A-55-45746), a material composed of polyamic acid and an amine compound having a photosensitive group (JP-A-54-145794) and the like. However, according to these proposals, since an imidation treatment at a high temperature of exceeding 300° C. is essential in order to obtain a polyimide film of interest after forming a patterned film, there was a problem in that the backing is limited and copper of the wiring is oxidized in order to withstand this high temperature.
As an improvement therefor, there has been proposed a photosensitive polyimide prepared using a solvent-soluble resin imitated in advance for the purpose of lowering the post-curing temperature (JP-A-10-274850, JP-A-10-265571 and JP-A-13-335619).
On the other hand, there has been proposed a positive type in which a polyimide backbone having phenolic hydroxyl group (JP-A-3-209478) or a polyamide backbone (JP-B-1-46862 and JP-A-11-65107) is combined with diazonaphthoquinone.
Also, regarding a product developed using a polyimide as the base resin and putting emphasis on the minute pattern formation, there is known a composition in which a side chain alcohol group of a ring-closed solvent-soluble polyimide and an alkoxy group-containing melamine compound undergo a photo-crosslinking by a photo-acid generator (JP-A-2006-133757).
However, all of the compositions described in JP-A-10-274850, JP-A-10-265571 and JP-A-13-335619 provide resins with photosensitivity making use of (meth)acrylic group, so that these could not become a material which satisfies all of the required characteristics because of a difficulty in improving resolution due to reasons based on the photo-curable mechanism, such as the aptness to receive oxygen damage, the aptness to cause membrane loss at the time of development, and the like.
In the case of the compositions described in JP-A-3-209478, JP-B-1-46862 and JP-A-11-65107, there were problems in that it is difficult to form a thick film of exceeding 10 μm in view of light permeability of the compositions, the resin molecular weight is small in order to secure the developing property, the original curing characteristics of the resins are difficult to obtain because the adding amount of diazonaphthoquinone as the photosensitive agent becomes large for the resins, and the like.
The composition described in JP-A-2006-133757 has a problem in that development cannot be carried out with an alkaline aqueous solution having fewer environmental loads.
In addition, in recent years, there is a demand in the field of wafer level semiconductor packaging techniques for a material which can form minute patterns and also has a function as an adhesive for attaching wafer substrates with each other. As such a curing resin composition which can form patterns, the following resins and their compositions have so far been reported.
For example, there has been reported a composition which contains a carboxyl group-containing polymer, a bismaleimide, an allyl group-containing polymer, an ethylenic unsaturated compound, an organic peroxide, a photopolymerization initiator and the like (JP-A-2006-323089). In addition, there has been reported a composition which contains a hydroxyl group- or carboxyl group-containing methacrylic modified bisphenol, an epoxy resin, a multifunctional acrylate and the like (JP-A-2009-9110).
Polyimide is famous as a resin which has high adhesiveness for silicon substrate and metal surface as well as heat resistance, and compositions using polyimide as the base resin have been reported (International Publication No. 2007/004569 and JP-A-2008-274269). Also, there has been reported a composition in which a carboxyl group-containing polyimide, an epoxy resin and a photo-base generator are combined (JP-A-2009-167381). In addition, regarding a product developed using a polyimide as the base resin and putting emphasis on the minute pattern formation, there is known by the aforementioned JP-A-2006-133757 a composition in which a side chain alcohol group of a ring-closed solvent-soluble polyimide and an alkoxy group-containing melamine compound undergo a photo-crosslinking by a photo-acid generator.
The compositions described in JP-A-2006-323089 and JP-A-2009-9110 are compositions which can perform patterning by an alkali development, but it cannot be said that they have sufficient performance regarding hardening ability, substrate adhering property at high temperature and reliability.
The compositions described in International Publication No. 2007/004569 and JP-A-2008-274269 are compositions composed of a polyimide having carboxyl group in the side chain thereof, a multifunctional acrylic substance, a photopolymerization initiator and the like. However, since the curing system is a crosslinking by radical polymerization, there is a possibility of causing reaction inhibition due to oxygen and there is a problem in that patterning ability at high sensitivity is insufficient and residual film at the time of development is also insufficient.
The composition described in JP-A-2009-167381 undergoes epoxy crosslink curing by a base generated by light and is excellent in attachability at low temperature but is insufficient regarding the minute patterning ability. In addition, the composition described in JP-A-2006-133757 is excellent as a wiring protecting film, but its adhesiveness of attaching substrates is not sufficient.